The use of certain substituted 8-phenylxanthine compounds as adenosine receptor antagonist agents is described in Proc. Natl. Acad. Sci. USA, 77, 5547 (1980). The reference discloses the use of 8-(4-sulfophenyl)theophylline, also named as 4-(1,3-dimethyl-2,3,6,7-tetrahydro-2,6-dioxo-1H-purin-8-yl)benzenesulfonic acid.